Decorative window coverings are a popular item for providing privacy and blocking light, which take on various forms. Two popular examples of window coverings are Roman shades and Venetian blinds.
A typical Roman shade consists of a fabric material attached along its top edge to a head rail and gathered at spaced intervals to provide a series of soft folds across the face of the fabric, which give it a cascaded or softly pleated appearance. Roman shades are constructed so that when they are raised, they gather from the bottom in generally horizontal folds or pleats until the entire shade resides near the top of the window covering. The shades are operated by pulling on various lines which are used in conjunction with guides attached to the shade.
One drawback to the typical Roman shade, however, is that there is no way to create openings in the overall face of the window covering if one wishes to permit light into a room, such as found in Venetian blinds by tilting the blind slats, without having to raise the bottom, or lower the top of the entire window covering, which undesirably results in a substantial loss of privacy. Therefore, it is desired to provide the ability to open gaps in the shade to allow light to pass, yet maintain a relatively high degree of privacy by not requiring the entire shade to be raised or lowered.
A conventional Venetian blind typically includes a head rail, a bottom rail, a plurality of slats, a raising mechanism including multiple raising cords, and a tilting or adjustment mechanism including multiple ladder strings. The lifting member typically comprises cords that are laterally symmetrically provided on the blind to balance the bottom rail and the slats for them to be lowered or lifted synchronously. By pulling the raising cords, the bottom rail and the slats are lifted or lowered relative to the head rail as desired.
The slats can be tilted upward or downward through operation of the tilting mechanism which adjusts the ladder strings. In this regard, each ladder generally includes a front and rear, and vertically-extending members or strings connected to each other by a plurality of vertically-spaced cross-rungs. Supported on each cross-rung, between the vertically-extending members of its ladder, is one length-wise side of a slat. The head rail generally includes this tilting or adjusting mechanism for moving the ladders, so that the vertically-extending members of each ladder move in opposite vertical directions relative to one another, to pivot each slat about its length-wise axis. By tilting the above-mentioned slats to a different angle of inclination, the amount and direction of light projected into a room through the Venetian blind can be controlled and adjusted.
Venetian blinds, however, have the aesthetic drawback that the ladder is partially visible from both the face and back of the blind when closed. This ladder undesirably disrupts the otherwise continuous appearance of the window covering. Also, holes for the raising and tilting cords may also be visible when the Venetian blind is closed. This again detracts from the aesthetic appeal of the window covering, as well as permits additional light to penetrate a room even when the blind slats are closed.